The Promise And Perils Of New Apple Watch Medical Technologies

The latest Apple Watch 4 features two new, potentially life-saving, health monitoring systems not seen before in consumer smart watches. The first is a built-in EKG (electrocardiogram) that is FDA approved to sense whether the wearer has a normal heart rhythm or “atrial fibrillation” — one of the more common abnormal rhythms.

Atrial fibrillation (or “AFib”) is a serious condition that should be treated by a trained physician. However, it can often appear and disappear intermittently, and may not be apparent while a patient is at a medical facility. If a patient is feeling any unusual “racing heartbeat” or unexplained shortness of breath with a pounding sensation in the chest, they can put their finger on their Apple Watch sensor and see if they are in AFib.

If the fall detection feature is activated and you take a hard spill, the watch will ask if you’re ok. If you don’t respond promptly, the watch takes stronger measures. According to Apple:

If your Apple Watch detects that you’re immobile for about a minute, it begins a 15-second countdown, while tapping you on the wrist and sounding an alert. The alert gets louder, so that you or someone nearby can hear it. When the countdown ends, your Apple Watch automatically contacts emergency services. Then it sends a message to your emergency contacts with your location letting them know that Apple Watch detected a hard fall and dialed emergency services.

I’m excited about both of these developments. As a physician, I love the idea of technologies that help users track their own health data and act on it as the user wishes.

However, there are some pitfalls that ordinary consumers should be aware of.

With respect to EKG monitoring, the watch could generate false positive readings — i.e., report that a patient has AFib when they actually don’t. Users with potential AFib are (correctly) advised to seek medical attention to confirm the provisional diagnosis. The Apple Watch is basically a crude single-lead EKG system, whereas the more accurate monitors in the hospital have 6 or 12 leads.

Hence, in a young healthy population, the likelihood that the watch is generating a false alarm may be higher than the likelihood that the watch has detected a relatively rare previously undiagnosed case of AFib.

As with any screening test where the underlying rate of the disease prevalence is fairly low, the incidence of true positives (people who actually have the disease) has to be weighed against false positives (where the the test falsely reports the disease but the patient is actually healthy). Such false positives can lead to unnecessary (albeit temporary) anxiety, as well as raise medical costs. Apple Watch users who may be on the hook for medical bills related to false alarms might wish to keep this in mind.

With respect to the fall detection system, there’s a similar problem of false positives, causing unnecessary alarm to one’s trusted contacts or to the emergency medical system.

In addition, the fall detection system could theoretically place some people at legal risk. According to Elizabeth Joh, a law professor at the University of California at Davis, if a user’s watch is programmed to call 911 and the police enter their home in response, then the police could also arrest the user if they detect any contraband or other evidence of a crime that happens to be in “plain sight.” Because the police were invited in (via the 911 request), the usual 4th Amendment protections against illegal search and seizure don’t apply.

These concerns over false positives or unusual legal risks shouldn’t stop users from taking advantage of these useful features. However, Apple Watch owners should weigh the relative risks and benefits in the context of their own personal circumstances and priorities.

Overall, I’m excited about this new trend in consumer medical technology, and I can’t wait to see what Apple and other companies come up with next.